This paper aims to develop an integrative theoretical explanation of organisational agility under uncertainty by identifying its fundamental capabilities and the mechanism regulating their situational interaction. The study adopts a conceptual research methodology based on an integrative analysis and synthesis of literature on Agile Manufacturing, enterprise agility, Agile Software Development, dynamic capabilities, entrepreneurship, opportunity recognition, and decision-making under uncertainty. The analysis distinguishes organisational capabilities from context-specific agile practices and process-based explanations. As a result, organisational agility is conceptualised as a morphology comprising four qualitatively distinct but interdependent capabilities: Brightness, Flexibility, Intelligence, and Shrewdness. They determine, respectively, the organisation's ability to perceive potentially relevant situations, configure resources, cognitively justify possible actions, and convert opportunities into value-creating outcomes. The study further identifies Opportunity Intelligence as a higher-order regulatory mechanism rather than an additional dimension of agility. It coordinates the morphology through five regulatory functions: direction, activation, configuration, feedback, and termination. The findings indicate that organisational agility does not result from maximising individual capabilities or continuously adapting to environmental change. It emerges from their selective, opportunity-specific configuration. The proposed framework therefore shifts the interpretation of agility from adaptive responsiveness towards purposefully regulated, opportunity-oriented organisational action under uncertainty.